The banded killifish (''Fundulus diaphanus'') is a North American
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout ...
freshwater killifish
A killifish is any of various oviparous (egg-laying) cyprinodontiform fish (including families Aplocheilidae, Cyprinodontidae, Fundulidae, Profundulidae and Valenciidae). All together, there are 1,270 species of killifish, the biggest family ...
belonging to the genus ''
Fundulus
''Fundulus'' is a genus of ray-finned fishes in the superfamily Funduloidea, family Fundulidae (of which it is the type genus). It belongs to the order of toothcarps (Cyprinodontiformes), and therein the large suborder Cyprinodontoidei. Most of ...
'' of the family
Fundulidae
Fundulidae is the family of topminnows and North American killifishes.
Distribution
The 46 species are native to North America as far south as Yucatan, and to the islands of Bermuda and Cuba, occurring in both freshwater and marine environments ...
. Its natural geographic range extends from
Newfoundland to
South Carolina
)'' Animis opibusque parati'' ( for, , Latin, Prepared in mind and resources, links=no)
, anthem = " Carolina";" South Carolina On My Mind"
, Former = Province of South Carolina
, seat = Columbia
, LargestCity = Charleston
, LargestMetro = ...
, and west to
Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
, including the
Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lak ...
drainages.
[Page, Lawrence M. and Brooks M. Burr (1991), ''Freshwater Fishes'', p. 216, Houghton Mifflin, New York. ] This species is the only freshwater killifish found in the northeastern United States. While it is primarily a freshwater species, it can occasionally be found in
brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estu ...
water.
Etymology
The common name, "banded killifish", commonly refers to the distinct black and white vertical bandings found along their sides. The Latin genus name ''
Fundulus
''Fundulus'' is a genus of ray-finned fishes in the superfamily Funduloidea, family Fundulidae (of which it is the type genus). It belongs to the order of toothcarps (Cyprinodontiformes), and therein the large suborder Cyprinodontoidei. Most of ...
'' is the diminutive of ''fundus'', which means "bottom," and the specific name ''diaphanus'' means "transparent" in
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
.
[Chippett, Jamie D. 2003. "Update COSEWIC status report on the banded killifish Fundulus diaphanus, Newfoundland population in Canada", in ''COSEWIC assessment and update status report on the banded killifish Fundulus diaphanous in Canada''. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-21 pp]
Description
![Banded killifish 2](https://upload.wikimedia.org/wikipedia/commons/5/5d/Banded_killifish_2.jpg)
The banded killifish has a narrow, elongate bluish-gray or olive-colored body with a darker dorsal surface and white or yellowish underparts extending to the anal fin.
Spawning males develop yellow pectoral and pelvic fins, a bright blue patch on the anal fin, and brilliant blue iridescence on the lower portion of the body including the area around the anal fin.
There are 12–20 vertical bands along the sides.
In females the bands usually appear as thin and distinct black bands that often do not span the full width of the body. In males, the bands are silvery in color, are less distinct, and are closer together. The number of bands are useful in sexing an individual; male banded killifish have a greater (approximately >9) number of bands anterior to the dorsal fin.
Fins rounded, base of first dorsal ray slightly ahead of or directly over first anal ray.
Snout is blunt, with small superior mouth and projecting lower jaw. Lateral line is missing; 39–43 scales in the lateral series.
10–13 dorsal fin rays, 9–11 anal fin rays, 6 pelvic fin rays. Max length TL, average length TL.
The eastern subspecies, ''F. d. diaphanus'', can be differentiated from the western subspecies, ''F. d. menona'', by the presence of a further anterior dorsal fin position, increased number of anterior bars in the males of the subspecies (9-15 compared to 5-0 for ''F. d. menona'') with more intense bars along the side that stay intact along the anterior back, a higher number of scale rows (40-44 ''F. d. menona'', 45-49 ''F. d. diaphanus''), and a combined number of dorsal and anal fin rays totaling 24-26, compared to 23-24 for ''F. d. menona''. Larger maximum sizes have been reported for ''F. d. diaphanus'' than ''F. d. menona''.
The banded killifish is similar in habitat preference and appearance to the
mummichog
The mummichog (''Fundulus heteroclitus'') is a small killifish found along the Atlantic coast of the United States and Canada. Also known as Atlantic killifish, mummies, gudgeons, and mud minnows, these fish inhabit brackish and coastal waters in ...
, ''Fundulus heteroclitus'', and the two species have been known to interbreed where their habitat overlaps. The banded killifish, while euryhaline, is more commonly found in freshwater, whereas the mummichog primarily inhabits brackish and coastal waters. The two species can be visually identified by the difference in bands; the banded killifish has thin dark bars, while the mummichog has thin light bars. The species can also be differentiated by the thicker caudal peduncle in the mummichog and branchiostegal rays often numbering 6,6 for the banded killifish (5,5 in the mummichog). Banded killifish have larger and more numerous gill rakers compared to mummichogs (8-12 vs. 4-7, respectively).
The Waccamaw killifish, Fundulus waccamensis, is a closely related species to the banded killifish that is endemic to Lake Waccamaw, North Carolina, and its tributaries. the Waccamaw killifish differs by its slimmer profile; the ranges of the two species do not overlap.
Range and distribution
The banded killifish is widely distributed throughout eastern North America, ranging from the Pee Dee River, South Carolina to Newfoundland; also found in southern Pennsylvania, northeastern Nebraska, and northern Illinois, and north to St. Lawrence-Great Lakes and Mississippi River basins from Manitoba to Quebec. The eastern subspecies is found on the Atlantic Slope, and the western subspecies in the rest of its range.
Westward expansion by the eastern subspecies may be the result of introductions as bait or aquarium fish into novel waterbodies, climate change expanding favorable habitat, or a higher pollution tolerance compared to the western subspecies.
The banded killifish was assigned a status of special concern by the
Committee on the Status of Endangered Wildlife in Canada
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC, French: Comité sur la situation des espèces en péril au Canada, COSEPAC) is an independent committee of wildlife experts and scientists whose "raison d'être is to identify s ...
(COSEWIC) due to biogeographical isolation and limitation of potential for range expansion.
In the United States, states Ohio and Illinois list the western subspecies as endangered and threatened, respectively, due to range expansion of the eastern subspecies which has been documented to hybridize wherever the ranges of the subspecies overlap. As such, Ohio also classifies ''F. d. diaphanus'' as an injurious aquatic invasive species. Intergrades occur in the Saint Lawrence and Lake Erie drainages where the ranges of the two subspecies naturally come in contact.
The banded killifish has been introduced outside of its native range in the states of Idaho, Ohio, Oregon, Pennsylvania, South Dakota, Washington, and West Virginia. In Oregon and Washington, the western banded killifish is reported to be the introduced subspecies.
Habitat and ecology
Adults range from 2 to 3 years in age. Banded killifish are
schooling fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
, usually traveling in groups of 3–6 individuals, while the
juveniles travel in groups of 8–12. The fish are most often found in the shallow and quiet areas of clear
lake
A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
s,
pond
A pond is an area filled with water, either natural or artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% emergent vegetation helps in distinguishing their ecology from ...
s,
river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...
s, and
estuaries
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...
with sandy gravel or muddy bottoms and with abundant aquatic vegetation. The sand and gravel provides
hatchlings and juveniles with places to hide when threatened by
predatory fish
Predatory fish are hypercarnivorous fish that actively prey upon other fish or aquatic animals, with examples including shark, billfish, barracuda, pike/muskellunge, walleye, perch and salmon. Some omnivorous fish, such as the red-bellied piranh ...
such as the largemouth bass ''
Micropterus salmoides
The largemouth bass (''Micropterus salmoides'') is a carnivorous freshwater gamefish in the Centrarchidae ( sunfish) family, a species of black bass native to the eastern and central United States, southeastern Canada and northern Mexico, but ...
'', northern pike ''
Esox lucius
The northern pike (''Esox lucius'') is a species of carnivorous fish of the genus ''Esox'' (the pikes). They are typical of brackish and fresh waters of the Northern Hemisphere (''i.e.'' holarctic in distribution). They are known simply as a p ...
'', bluegill ''
Lepomis macrochirus
The bluegill (''Lepomis macrochirus''), sometimes referred to as "bream", "brim", "sunny", or "copper nose" as is common in Texas, is a species of North American freshwater fish, native to and commonly found in streams, rivers, lakes, ponds and ...
'', and
trout
Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salm ...
. Because the banded killifish is small, it generally does not venture into deeper waters, where it would be vulnerable to
predation
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
as well as unable to swim in the fast currents. However, adult banded killifish have been observed to travel into deep bodies of water to feed. Banded killifish often congregate near aquatic vegetation, as it provides protection as well as breeding habitat.
Banded killifish are
euryhaline, but they usually inhabit freshwater streams and lakes. The largest adult recorded, observed in
Indian Bay, Canada, was . People have used banded killifish as
fish bait
Fishing bait is any substance used to attract and catch fish, e.g. on a fishing hook. Bait items are both selected from and placed within the environment to achieve enhanced prey capture success. Traditionally, fishing baits are natural fish foo ...
. Most people do not favor them as pets because they require a high level of maintenance and therefore do not survive well in an
aquarium setting. They are important to aquatic
ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
s because they are a food source for larger fish such as largemouth bass, northern pike, and trout. They are also a food source for birds such as belted kingfisher (''
Megaceryle alcyon
The belted kingfisher (''Megaceryle alcyon'') is a large, conspicuous water kingfisher, native to North America. All kingfishers were formerly placed in one family, Alcedinidae, but recent research suggests that this should be divided into three ...
''), common merganser (''
Mergus merganser''), and
herons.
In January 2005 the banded killifish was listed as a vulnerable species under the Newfoundland Labrador Endangered Species Act and the Canada
Species at Risk Act
The ''Species at Risk Act'' (SARA) (the ''Act'') is a piece of Canadian federal legislation which became law in Canada on December 12, 2002. It is designed to meet one of Canada's key commitments under the International Convention on Biological D ...
(SARA). This species is facing habitat degradation due to industrial development, motorized watercraft activities, and removal of aquatic vegetations.
Diet
Banded killifish have been observed to feed at all levels of the water column. The adults feed on a variety of items such as
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...
s, nymphs,
mollusks,
turbellarians
The Turbellaria are one of the traditional sub-divisions of the phylum Platyhelminthes (flatworms), and include all the sub-groups that are not exclusively parasitic. There are about 4,500 species, which range from to large freshwater forms more ...
, and other small
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...
s.
Mosquito
Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...
larvae are also a popular food source. In contrast, the smaller individuals are limited to fewer items such as
chironomid
The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many specie ...
larvae,
cladoceran
The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms).
Over 1000 species have been recognised so far, with many more ...
s,
copepods, and
midge larvae. Both young and adult banded killifish have been observed to feed mostly in the afternoon.
[Paulson, N. and Jay T. Hatch](_blank)
/ref>
Reproduction and life cycle
Banded killifish are commonly observed to spawn
Spawn or spawning may refer to:
* Spawn (biology), the eggs and sperm of aquatic animals
Arts, entertainment, and media
* Spawn (character), a fictional character in the comic series of the same name and in the associated franchise
** '' Spawn: ...
in dense aquatic vegetation because they practice external fertilization
External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body.
It is contrasted with internal fertilization, in which sperm are introduced via insemination and then ...
where the female lays her eggs that are equipped with adhesive threads that adhere to plants. Spawning occurs from June to mid-August in shallow waters. During the spawning season, the males go through a color change phase. They develop a bright blue patch near the anal fin. In addition, the lower portion of the body changes to a bright blue color.
Spawning occurs at water temperatures of 21˚ C to 23˚ C. The male chooses a site in the shallow part of the water and protects it from other males. When a female appears, the male will court the female and fight with the other prospecting males. The female will emit one egg while the male pursues her. Once together, the female emits 10 eggs that falls onto the bottom or gets attached to aquatic plants in the chosen spawn area. The male will continue to pursue the female until the female have laid 50 to 100 eggs.
A single female may lay several clutches
A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts) ...
of eggs during one summer. After the eggs have been fertilized, both the parents will leave and go their separate ways; the eggs do not receive parental care. Fries
French fries (North American English), chips (British English), finger chips ( Indian English), french-fried potatoes, or simply fries, are '' batonnet'' or ''allumette''-cut deep-fried potatoes of disputed origin from Belgium and France. Th ...
( in length) emerge within 10 to 12 days depending on the temperature of the water. They reach maturity at approximately 1 year with an average length of . Banded killifish can live for a little over 2 years. However, there have been some that have been observed to live up to 3 years.
Behavior
Shoaling behavior
Banded killifish form group shoals
In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. I ...
. The conditions in which shoaling occurs, the individuals who comprise the shoal, and the size of the shoal are all highly variable. Shoaling can be understood through a cost and benefit analysis. The costs and benefits of group membership are influenced by food availability and predatory risk. Bigger groups allow for better predatory protection, but are not as conducive to foraging
Foraging is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce. Foraging theory is a branch of behavioral ecology that studies the foraging behavi ...
because the food will be distributed amongst all of the group members. For smaller groups, there is not as effective predatory protection, but in regards to foraging each individual will have access to more food.
The nutritional state of banded killifish influences individual's decisions to shoal or not. Food-deprived individuals spent more time by themselves and not in shoals. When food-deprived individuals were found in shoals their shoals were not any smaller than that of a well-fed banded killifish. Hungry banded killifish are more likely to leave a shoal than a well-fed individual.
In the presence of a food stimulus, group size decreases, so that each individual does not have to compete
Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...
with others for access to these resources. When presented with food odour, individuals were less attracted to neighbors, but when presented with a predatory stimulus, they were more attracted to neighbors and formed tighter shoals. When in the presence of both stimuli, the group size is intermediate.
In the presence of a predatory stimulus, banded killifish decrease the amount of food attempts and duration of feeding posture. This is done to allocate more energy to predatory vigilance and avoidance. In both the presence and absence of predatory stimuli, banded killifish feeding rate for individuals is independent of shoal size. Lone individuals incur additional cost because they do not gain the improved predatory protection granted by shoal formation, and thus will attempt to join larger shoals rather than smaller shoals. When deciding whether to join a shoal or not, banded killifish value predatory protection over foraging opportunities.
Predator protection
In the presence of a predatory stimulus, shoal size increases to allow for greater protection via the dilution effect. From the dilution effect, each individual will have a lesser chance of being attacked by a predator, since there are many other individuals in the group. In a larger group, there is a larger chance that a predator will attack a different shoalmate than it will attack the individual of interest. Individuals who stray from the shoal have an increased mortality risk. This leads to selection
Selection may refer to:
Science
* Selection (biology), also called natural selection, selection in evolution
** Sex selection, in genetics
** Mate selection, in mating
** Sexual selection in humans, in human sexuality
** Human mating strateg ...
for grouping.
Besides the dilution effect, shoaling also benefits the individual because of group vigilance. To best protect against predation, the banded killifish must be on the lookout to detect predators. In a group, each individual can spend less time looking out for predators because others in the shoal can share in this responsibility. With increasing shoal size, each individual spends less time being vigilant, but with more individuals the group increases overall vigilance and therefore benefit each individual in the shoal. When one individual detects a predator, an alarm call
In animal communication, an alarm signal is an antipredator adaptation in the form of signals emitted by social animals in response to danger. Many primates and birds have elaborate alarm calls for warning conspecifics of approaching predator ...
is made to alert the shoal, so that the individuals can act to protect themselves from predatory attack.
To improve predator avoidance, banded killifish will often take refuge. Frightened fish in the presence of a predatory stimulus will hide in a foodless refuge. This preference is modulated by individual body size. Larger individuals spend more time in the refuge than their smaller conspecifics
Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species.
Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...
. Smaller banded killifish individuals are more prone to risk than their larger counterparts.
Shoaling preferences
When choosing which shoals to join, banded killifish often choose to join ones that consist of others with similar phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...
s. In order to achieve this, banded killifish have shown the ability to discriminate between individuals within the species. Banded killifish distinguish individuals by body coloration phenotype. Banded killifish are likely to enter shoals with those of similar body color in order to maximize predator avoidance. An individual of different color might present as a contrast. This contrast is likely to make the shoal stand out and gain the predator's attention. Banded killifishes' level of preference for similarly colored shoalmates differs in the presence and absence of a predatory stimulus.
Banded killifish use body coloration to determine if an individual has been parasitized or not. Black spots indicate the presence of a parasite, whereas the absence of these spots indicates an unparasitized individual. Both parasitized and unparasitized individuals preferred to join unparasitized shoals. The preference for unparasitized shoals increases with an increase in parasite load of a parasitized individual.
Shoaling preferences in banded killifish differ in shoal species composition, shoal size, and individual body size within the shoal. The shift in preferences is triggered by predatory stimuli. In the presence of predatory stimuli, a banded killifish individual will prefer the bigger conspecific shoal, but only as long as the shoal is homogenous in individual fish size. If the size of individual fish were different, they would join a shoal of similarly sized fish regardless of shoal size. This preference is maintained by predatory threat. Body size is a more significant determinant of shoaling preference than shoal size and species composition.
Banded killifish have been found to engage in heterospecific shoaling with other species of killifish as well as other fish. There are many situational factors that determine if the banded killifish individual would want to engage in heterospecific shoaling. If body size is similar, then banded killifish prefer conspecific shoals as opposed to heterospecific ones. Size is a sorting mechanism for conspecific as opposed to heterospecific shoaling.
References
External links
Banded Killifish Newfoundland and Labrador Population article
eNature article
Lake George Fact Sheet
Ohio Department of Natural Resources Division of Wildlife
USGS
WILLIAM J. POLY AND ROBERT J. MILTNF.R, Department of Zoology, Southern Illinois University, Carbondale, Illinois 62901 and Ohio Environmental Protection Agency, Ecological Assessment Section, 1685 Westbelt Drive, Columbus, Ohio 43228
{{Taxonbar, from=Q3075950
Banded killifish
Freshwater fish of the United States
Taxa named by Charles Alexandre Lesueur
Fish of Canada
Fish of the Eastern United States
Fauna of the Northeastern United States
Fauna of the Plains-Midwest (United States)
Fauna of the Southeastern United States
Least concern biota of North America
Least concern biota of the United States
Fish described in 1817